Expandable Trial Assembly For Expandable Vertebral Implant

ABSTRACT

The present invention relates to a method of inserting an implant comprising providing a trial assembly. The method may further comprise positioning the trial assembly between vertebrae in a patient. The method may further comprise rotating a drive shaft of the trial assembly to cause upper and lower gear members of the trial assembly to rotate causing expansion of a tip assembly of the trial assembly. The method may further comprise measuring expansion of the trial assembly with a scale at a proximal end of the trial assembly. The method may further comprise removing the trial assembly from the patient. The method may further comprise positioning an implant between the vertebrae in the patient. The method may further comprise expanding the implant based on the measured expansion of the trial assembly.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present invention is a continuation-in-part of U.S. patentapplication Ser. No. 13/333,227, entitled “Expandable VertebralImplant,” filed on Dec. 21, 2011, which is a continuation-in-part ofU.S. patent application Ser. No. 12/758,529 entitled “ExpandableVertebral Implant” filed on Apr. 12, 2010, the entire disclosure ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to a device to support the spine afterremoval of at least a part of a vertebra.

BACKGROUND OF THE INVENTION

When a vertebra is damaged or diseased, surgery may be used to replacethe vertebra or a portion thereof with a prosthetic device to restorespinal column support. For example, vertebral body replacement iscommonly required in the treatment of vertebral fracture, tumor, orinfection.

In recent years, several artificial materials and implants have beendeveloped to replace the vertebral body, such as, for example, titaniumcages, ceramic, ceramic/glass, plastic or PEEK, and carbon fiberspacers. Recently, various expandable prosthetics or expandable cageshave been developed and used for vertebral body replacement. Theexpandable prosthetic devices are generally adjustable to the size ofthe cavity created by a corpectomy procedure and typically are at leastpartially hollow to accommodate bone cement or bone fragments tofacilitate fusion in vivo. Some expandable implants may be adjustedprior to insertion into the cavity, while others may be adjusted insitu. Two advantages of the vertebral body replacement using anexpandable prosthetic device that is adjustable in situ is that it iseasy to place or insert and it permits an optimal, tight fit andcorrection of the deformity by in vivo expansion of the device. Someother advantages offered by an expandable prosthetic device are thatthey can facilitate distraction across the resected vertebral defect forcorrection of the deformity, and allow immediate load bearing aftercorpectomy.

Instrumentation and specialized tools for insertion of a vertebralimplant is one important design parameter to consider when designing avertebral implant. Spinal surgery procedures can present severalchallenges because of the small clearances around the prosthetic when itis being inserted into position. Another important design considerationincludes the ability of the device to accommodate various surgicalapproaches for insertion of the vertebral implant.

SUMMARY OF THE INVENTION

The present invention relates to an expandable prosthetic implant devicefor engagement between vertebrae generally comprising an inner member,outer member, and gear member positioned coaxial with respect to eachother such that the inner and outer members are moveable relative toeach other along an axis. The inner member has a hollow interior portionand a threaded external portion and includes a first end portionconfigured to engage an endplate which is capable of engaging a firstvertebral body. The outer member has a hollow interior portionconfigured to receive the inner member and includes a second end portionconfigured to engage an endplate which is capable of engaging a secondvertebral body. The gear member is axially fixed to the outer member andfreely rotatable with respect to the outer member and the gear memberthreadedly engages the threaded portion of the inner member.

The implant is configured to engage the vertebrae such that first andsecond end portions are oriented in a predetermined alignment withrespect to the first and second vertebral bodies. The gear memberincludes teeth extending around the perimeter of the gear member and theteeth are exposed to the exterior and configured to be accessible by atool member.

The present invention further relates to a method of inserting animplant comprising providing a trial assembly. The method may furthercomprise positioning the trial assembly between vertebrae in a patient.The method may further comprise rotating a drive shaft of the trialassembly to cause upper and lower gear members of the trial assembly torotate causing expansion of a tip assembly of the trial assembly. Themethod may further comprise measuring expansion of the trial assemblywith a scale at a proximal end of the trial assembly. The method mayfurther comprise removing the trial assembly from the patient. Themethod may further comprise positioning an implant between the vertebraein the patient. The method may further comprise expanding the implantbased on the measured expansion of the trial assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more readily understood with reference tothe embodiments thereof illustrated in the attached drawing figures, inwhich:

FIG. 1 is a perspective view of an implant in accordance with anembodiment of the present invention;

FIG. 2 is an exploded view of the implant of FIG. 1;

FIG. 3 is a cross-sectional view of the implant of FIG. 1 taken alongline 3-3 of FIG. 1;

FIG. 4 is perspective view of an embodiment of an inner member of theimplant of FIG. 1;

FIG. 5 is perspective view of an embodiment of an outer member of theimplant of FIG. 1;

FIG. 6 is an elevated perspective view of one embodiment of a gearmember of the implant of FIG. 1;

FIG. 7 is a bottom perspective view of the gear member of FIG. 6;

FIG. 8 is a perspective of one embodiment of a tool according to thepresent invention;

FIG. 9 is a cross-sectional view of the tool of FIG. 8 shown engaging anembodiment of an expandable implant according to the present invention;

FIG. 10 is a perspective view of another embodiment of an implantaccording to the present invention; and

FIG. 11 is a perspective view of another embodiment of an endplate of animplant according to the present invention;

FIG. 12 is an exploded view of the endplate of FIG. 11;

FIG. 13 is a cross-sectional view of the endplate of FIG. 11;

FIG. 14 is a perspective view of an angling inserter tool of oneembodiment of the present invention;

FIG. 15 is an exploded view of the angling inserter tool of FIG. 14;

FIG. 16 is a top view of the angling inserter tool of FIG. 14;

FIG. 17 is a cross-sectional view of the angling inserter tool of FIG.14;

FIG. 18 is a cross-sectional view of one embodiment of a tip assembly ofthe angling inserter tool of FIG. 14;

FIG. 19 is an exploded view of the tip assembly of FIG. 18;

FIG. 20 is an elevated partial exploded view of the tip assembly of FIG.18;

FIG. 21 is another partial exploded view of the tip assembly of FIG. 18;

FIGS. 22 and 23 are top views of one embodiment of the angling insertertool of FIG. 14 showing angulation of the tip assembly;

FIG. 24 is a view of an expandable trial assembly of one embodiment ofthe present invention in a contracted position;

FIG. 25 is a cross-sectional view of the expandable tip assembly of theexpandable trial assembly of FIG. 24 in a contracted position;

FIG. 26 is a view of the expandable trial assembly of FIG. 24 in anexpanded position;

FIG. 27 is a cross-sectional view of the expandable tip assembly of theexpandable trial assembly of FIG. 24 in an expanded position;

FIG. 28 is a cross-sectional view of one embodiment of the proximal endof the expandable trial assembly of FIG. 25 showing the scale portion;and

FIG. 29 is a view of one embodiment of the proximal end of the trialassembly of FIG. 25 showing the scale portion.

Throughout the drawing figures, it should be understood that likenumerals refer to like features and structures.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the invention will now be described withreference to the attached drawing figures. The following detaileddescription of the invention is not intended to be illustrative of allembodiments. In describing preferred embodiments of the presentinvention, specific terminology is employed for the sake of clarity.However, the invention is not intended to be limited to the specificterminology so selected. It is to be understood that each specificelement includes all technical equivalents that operate in a similarmanner to accomplish a similar purpose.

Referring to FIGS. 1-6, a preferred embodiment of an expandablevertebral implant 10 is shown. The implant 10 preferably comprises aninner member 12 which may be telescopingly received within an outermember 14. The implant 10 further comprises a gear member 16 generallyconfigured to effect translation of the inner member 12 with respect tothe outer member 14 thereby allowing for expansion and contraction ofthe implant 10. The inner member 12, the outer member 14, and the gearmember 16 are preferably centered along a longitudinal axis 18 anddefine a hollow interior portion which may be filled with bone material,bone growth factors, bone morphogenic proteins, or other materials forencouraging bone growth, blood vessel growth or growth of other tissuethrough the many apertures in the device. In one preferred embodiment,members 12, 14, and 16 are made of a polyether ether ketone (PEEK)plastic material. There are several known advantages of PEEK plasticmaterial including being radiolucent, having a mechanical strength thatis close to bone, and may be more easily sterilized than other plastics.In alternate preferred embodiments, the members 12, 14, and 16 may bemade of a biologically inert metal alloys, such as titanium, or othersuitable materials.

Referring to FIGS. 1-5, the inner member 12 has a generally cylindricalbody 24 with a distal end 22 and a proximal end 36. In a preferredembodiment, the body 24 of the inner member 12 comprises an innersurface 28 and an outer surface 30 and generally defines a hollowinterior portion 23 extending axially therethrough. At least part of theouter surface 30 preferably includes external threads 32. Locatedproximate to the distal end 22 of the body 24 are a plurality of tabs 38which assist in connecting and positionally locating an endplate 20. Ina preferred embodiment, the body 24 is configured and dimensioned to becooperatively received within outer member 14.

The outer member 14 has a generally cylindrical body 40 with a distalend 42 and a proximal end 44. In a preferred embodiment, the body 40 ofthe outer member 14 comprises an inner surface 46 and an outer surface48 and generally defines a hollow interior portion 50 extending axiallytherethrough. The outer surface 48 preferably has at least one slot 52and an opening 54 configured and dimensioned to receive a portion of animplantation tool. In a preferred embodiment, the opening 54 extendsfrom the outer surface 48 to the hollow interior portion 50 and at leasta portion of the opening 54 is threaded. As best seen in FIG. 5, theinner surface 46 includes a channel 57 for receiving a locking member(discussed below). Located proximate to the proximal end 44 of the outermember 14 are a plurality of tabs 60 which assist in connecting andpositionally locating an endplate 62. In a preferred embodiment, a lip62 is formed around the exterior of the distal end 42 of body 40 and isconfigured to cooperatively fit with a portion of the gear member 16. Aplurality of relief spaces or slots 63 are radially spaced around lip 62to facilitate a snapping engagement of the lip 62 with the gear member16. In this regard, slots 63 allow the lip 62 to deform slightly andcontract in the radial direction to accommodate gear member 16 to snapon to lip 62. In a preferred embodiment, the interior portion 50 of body44 is configured and dimensioned to cooperatively receive body 24 ofinner member 12 within outer member 14. In this regard, the dimensionsof interior portion 50 of body 44 are greater than dimensions of body 24of inner member 12.

As best seen in FIGS. 2-5, in a preferred embodiment of a prostheticdevice 10, the body 24 of the inner member 12 includes a flattenedportion 34 which extends at least in part from the distal end 22 to theproximal end 36 and includes a base member 37 having at least one lobe39 located proximate to the distal end 36 of the body 24. Focusing onFIG. 5, the body 40 of the outer member 14 includes a flattened area 56and at least one depression 58 on the inner surface 46. When the innermember 12 is assembled within the outer member 14, the flattened area 56of the outer member 14 cooperatively aligns with the flattened portion34 of the inner member 12 and the at least one depression 58 of outermember 14 receives the at least one lobe 39 of the inner member 12. Theflattened portion 34 and the flattened area 56 along with the lobes 39and the depressions 58 cooperate to allow the inner member 12 tolinearly move with respect to the outer member 14 but prevent the innermember 12 from rotating with respect to the outer member 14. Inaddition, the base member 37 serves as a stop preventing the innermember 12 from rotating to a point of disengagement from outer member14.

Referring now to FIGS. 6-7, a gear member 16 comprises a generallyhollow body 64 extending from a distal end 66 to a proximal end 68 witha helical thread 70 along at least part of an inner wall 72 and an arrayof gear teeth 74 along a portion of the exterior wall 75. The gearmember 16 is generally configured to rotatably connect to the distal end42 of the outer member 14 and the internal helical thread 70 isconfigured to engage the external threads 32 of the inner member 12 tocause translation of the inner member 12 with respect to the outermember 14. In a preferred embodiment, the gear member 16 includes acylindrical cutout feature 76 extending around the inner wall 64 tocooperatively receive the lip 54 of the outer member 14. In this regard,the gear member 16 may rotate freely with respect to the outer member 14while being retained from longitudinal and lateral movement. In apreferred embodiment, the gear member 16 also includes a series ofcutouts 73 located proximate to the proximal end 68 for engaging aportion of a locking member.

With continued reference to FIGS. 6-7, the gear teeth 74 extendsubstantially from the proximal end 68 to the distal end 66 and extendaround the entire periphery of at least a portion of the exterior wall75. The outer-most external diameter 78 of the gear member 16 is sizedto be the same as or slightly smaller than the smallest outer diameterof the endplates 20, 62 and the outer member 14. In this regard, whenthe implant 10 is viewed from the end in a plane perpendicular to thelongitudinal axis 18, the gear member 16 does not protrude radiallyoutward from beyond the perimeter of the endplates 20, 62.

As shown in FIG. 7, in a preferred embodiment, the gear teeth 74 extenda width 80 in a generally radial direction and generally extend radiallyoutward to the outer diameter of the gear member 16. In this regard, theteeth 74 may be designed to have a width 80 to accommodate the expectedgear forces given the particular gear ratio, types of material used, anddesired overall diameter of prosthetic device 10. One skilled in the artwill appreciate that the larger the outer diameter to which the teeth 74radially extend, the larger the teeth 74 may be designed while stillmaintaining the same gear ratio. In this regard, when the teeth 74 aremade larger, they generally have a better mechanical strength. Also, theability to design larger, wider, and stronger teeth 74 is advantageousfor embodiments where the implant 10 is made of PEEK, other plastic, orother non-metallic materials that may have less mechanical strengththan, for instance, titanium.

Furthermore, as described in one embodiment, because the outer-mostdiameter of the gear member 16 may be as large as the outer diameter ofthe endplates 20, 62, and the teeth 74 extend radially to the outer-mostdiameter of the gear member 16, a larger inner diameter of the gearmember 16 may be manufactured without compromising mechanical gearstrength. As a result, a larger overall inner diameter of the implant 10may be accommodated which allows the packing of more bone materialtherein and facilitates bone fusion once the implant 10 is implanted.

As seen in FIGS. 1-3, in a preferred embodiment, the teeth 74 areexposed to the exterior of prosthetic device 10. Because the teeth 74are exposed around the periphery, little to no material is needed tocover up the exposed teeth, which generally makes the implant 10 lighterand easier to manufacture than prior art devices that require coveringthe gear teeth. In addition, the gear member 16 is more easily visibleby a surgeon and more readily accessible by a rotation tool than devicesthat hide or cover gear teeth.

Referring to FIGS. 2, 5, and 7, in a preferred embodiment, the implant10 also includes a locking member 80. The locking member 80 may beprovided to substantially restrict all relative movement between innermember 12 and outer member 14, when, for example, the desired expansionof the prosthetic device 10 has been obtained. The locking member 80 hasa body portion 82 with a through-hole 84. In a preferred embodiment, thebody portion 82 has at least one, but preferably two, outwardlyextending, flexible arms 86, 88 and at least one engagement member 90.In other preferred embodiments, instead of flexible arms 86, 88, it iscontemplated that the locking member 80 may include an alternate biasingmember, such as a leaf spring. The locking member 80 is configured anddimensioned to be received in the channel 57 of the outer member 14 insuch a manner that the arms 86,88 rest against a shelf portion in thechannel 57 and the through-hole 84 partially aligns with opening 54. Theengagement member 90 preferably protrudes upwardly and is configured anddimensioned to engage the cutouts 73 of the gear member 16 to preventthe gear member 16 from rotating.

Referring now to FIGS. 1-3, in a preferred embodiment, the endplates 20,62 are shown wherein the endplate 20 connects to the inner member 12 andendplate 62 connects to the outer member 14. In a preferred embodiment,endplate 20 includes an extension portion 91 which is received in theinterior portion 23 of inner member 12, for example, in an interferenceor snap fit and includes a plurality of tabs 93 which interdigitate withtabs 38 to connect and position endplate 20 with respect to the innermember 12. Endplate 62 includes an extension portion 95 which engagesthe proximal end 44 of the outer member 14, for example, in aninterference or snap fit and includes a plurality of tabs 97 whichinterdigitate with tabs 60 to connect and position endplate 62 withrespect to the outer member 14. The endplates 20, 62 also preferablyinclude hollow interior portions 99, 101 which are in fluidcommunication with the hollow interior portions 23, 50 of inner member12 and outer member 14, respectively.

In a preferred embodiment, each endplate 20, 62 is generally annular inshape when viewed from the end or perpendicular to the longitudinal axis18. It is, however, contemplated that the endplates 20, 62 can be othershapes including oblong, elliptical, kidney bean, polygonal, orgeometric. Preferably, the endplates 20, 62 are designed to resemble ormimic the footprint of the vertebral body to which the endplates willengage. In this regard, endplates 20, 62 are configured to engageportions of the vertebrae in a predetermined orientation to maximizecontact of the superior surface of the endplates 20, 62 with bone.

The dimensions of endplates 20, 62 can be varied to accommodate apatient's anatomy. In some embodiments, the endplates 20, 62 have awedge-shaped profile to accommodate the natural curvature of the spine.In anatomical terms, the natural curvature of the lumbar spine isreferred to as lordosis. When implant 10 is to be used in the lumbarregion, the angle formed by the wedge should be approximately between3.5 degrees and 16 degrees so that the wedge shape is a lordotic shapewhich mimics the anatomy of the lumbar spine. In alternate embodiments,the wedge shape profile may result from a gradual increase in heightfrom an anterior side to a posterior side to mimic the naturalcurvature, kyphosis, in other regions of the spine. Thus, in otherembodiments, the angle may be between about −4 degrees and −16 degrees.

As shown in FIGS. 1-3, in a preferred embodiment, the endplates 20, 40include a plurality of mounting holes 92 spaced around the perimeter ofeach endplate 20, 40 for receiving insertable bone engaging members 94.In one embodiment, bone engaging members 94, comprise conical spikes 96each having a cylindrical base portion 98 configured to fit within holes92, for instance, by press-fit or by threaded engagement. In alternateembodiments, differently shaped bone engaging members 100 may be used,or in other embodiments no bone engaging members may be used. Referringagain to FIG. 2, according to one embodiment, endplates 20, 62 havechamfered edges 100 around the perimeter to facilitate insertion and/oraccommodate the shape of the vertebral bodies which they engage. Thesuperior or bone engaging surfaces 102, 104 of endplates 20, 62 may alsoinclude numerous types of texturing to provide better initial stabilityand/or grasping contact between the end plate and the respectivevertebrae. In a preferred embodiment, the texturing is a plurality ofteeth 106. In preferred embodiments where the implant 10 is manufacturedfrom PEEK or other plastic materials, the endplates 20, 62 may alsoinclude radio-opaque material, such as tantalum markers 108, which aidin providing location markers in radiographic images.

In preferred embodiments, the length, diameter, and shape of prostheticdevice 10 may vary to accommodate different applications, differentprocedures, implantation into different regions of the spine, or size ofvertebral body or bodies being replaced or repaired. For example,implant 10 may be expandable to a longer distance to replace multiplevertebral bodies. Also endplates 20, 62 can be sized and shaped as wellas positioned to accommodate different procedures and approached to thespine. For example, endplates 20, 62 may be made smaller for smallerstatured patients or for smaller regions of the cervical spine. Inaddition, it is not required that endplates 20, 62 be shaped and sizedidentically and in alternate embodiments they can be shaped or sizeddifferently than each other and/or include different bone engagingmembers or texturing.

Turning now to FIGS. 8-9, the implant 10 may be expanded by a tool 110that includes a gear member 112 at its distal end 114. The tool 110extends along a tool axis 114 and in operation the tool 110 isconfigured to engage the implant 10 such that the tool axis 114 isgenerally perpendicular to the longitudinal axis 18. The gear member 112is configured to engage teeth 74 of the gear member 16 such that whenthe gear member 112 is rotated about the axis of the tool 110, the gearmember 16 of the implant 10 is rotated about the longitudinal axis 18and the inner member 12 translates along the longitudinal axis 18 toeither expand or contract the implant 10. In a preferred embodiment, thetool 110 may include a central shaft 116 having a threaded distal tipportion 118 that extends distally beyond gear member 112 to facilitatelocation and mounting of tool 110 with the implant 10. The threadeddistal tip portion 118 preferably includes a generally conical endportion and may be configured to extend radially through the opening 54and threadably engage opening 54 in the outer member 14.

With continued reference to FIGS. 8-9, in one embodiment of prostheticdevice 10 at least one, but preferably a plurality of mounting featuresor slots 52 are provided along the outer surface 48 of outer member 14.The tool 110 includes at least one, but preferably two, articulatingarms 120, 122 that engage slots 52 for better engagement of the tool 110with the implant 10 during insertion of the implant 10. In anotherpreferred embodiment, the tool 110 may include arms 120, 122 that do notarticulate.

In an exemplary use of the tool 110 with the implant 10, the tool 110initially engages the slots 52 of the implant 10 via the arms 120, 122and gear member 112 engages gear member 16 via their respectiveinterdigitating teeth. A control member on the proximal end of the tool110 (not shown) is manipulated to advance the central shaft 116 towardopening 54. The threaded tip portion 118 enters into opening 54 engagingthe threads in opening 54 as well as engaging the through-hole 84 oflocking member 80. It is also contemplated that the central shaft 116 isnot movable with respect to the tool 110. In that embodiment, the entiretool 110 is moved so that the central shaft can enter and engage theopening 54 and the through-hole 84. As discussed earlier, thethough-hole 84 is offset from opening 54, thus, when threaded tip 118engages and advances into the opening 54 and the through-hole 84, thelocking member 80 is pulled downwardly, riding along the conical edge ofthe tip 118 until the through-hole 84 is aligned with the opening 54. Asthe locking member 80 is pulled downwardly, the arms 82, 84 are flexedand the engagement member 90 disengages from the cutout 73 of the gearmember 16 allowing the gear member 16 to rotate freely. The gear member112 of tool 110 is then rotated via opening 114 which, in turn, rotatesgear member 16. As discussed above, the rotation of gear member 16results in the movement of inner member 12 causing the implant 10 toeither expand or contract, depending on the direction the gear member 16is rotated. Once the desired height for implant 10 is achieved, the toolmember 110 is disengaged from implant 10. When the tool 110 is removed,the locking member 80 returns to the back to its initial positionbecause of the arms 82, 84 returning back to their unflexed, at-reststate. The initial position of locking member 80 prevents the gearmember 16 from turning because of the engagement of engagement member 90with the cutouts 73. In that regard, implant 10 is locked from movementwhen the locking member 80 is in its initial position.

The benefit provided by the present locking mechanism is that it allowsfor a positive lock that engages and disengages automatically with theengagement and disengagement of the tool 110 with the implant 10, whichminimizes the steps the surgeon must perform during the procedure.

Referring now to FIGS. 10-13, alternate preferred embodiments ofendplates for the expandable implant 10 are shown. Looking at FIG. 10,in one variation, the endplates 202 and outer member 204 each include atleast one screw hole 206, 208, but, preferably, each include two screwholes. The screw holes 206, 208 are configured and dimensioned toreceive screws 210, 212. In a preferred embodiment, the screw holes 206,208 are angled such that when the screws 210, 212 are seated in thescrew holes 206, 208, the screws 210, 212 will extend outwardly from thesuperior surface 214 of endplate 202 and inferior surface 216 of outermember 204. Endplate 202 and outer member 204 also preferably include alocking element 218, 220 which, in a first position, allow the screws210, 212 to back out from the seated position and, in a second position,block the screws 210, 212 from backing out of the seated position. In anexemplary use, once the implant 200 is installed and expanded to thedesired position, the screws 210, 212 can be installed through the screwholes 206, 208 in such a manner as to purchase into the adjacentvertebral bodies. Once the screws 210, 212 are properly installed,including being engaged with the adjacent vertebral bodies, the lockingelements 218, 220 can be actuated to block the screws 210, 212 frombacking out of their installed position. The inclusion of screws 210,212 in the endplate 202 and the outer member 204 provides for additionalfixation of the implant 200 in the intervertebral space.

Turning to FIGS. 11-13, another preferred embodiment of an endplate 250is shown. The endplate 250 is similar to endplate 20 but includes theadditional functionality of being poly-axially rotatable with respect toan implant. In a preferred embodiment, endplate 250 includes a generallyarcuate extension portion 252 which is received in an interior portion253 of a receiving member 254 in such a manner as to allow the endplate250 to move poly-axially with respect to the receiving member 254.

In a preferred embodiment, the receiving member 254 is received in aninterior portion 255 of a locking ring 256. The receiving member 254preferably includes a neck portion 258 as well as a plurality of tabs260. The neck portion 258 is configured and dimensioned to be receivedwithin a hollow interior of an inner member, for example, in aninterference or snap fit, and the plurality of tabs 260 interdigitatewith tabs to connect and position the receiving member 254 with respectto an inner member. The receiving member 254 further includes aplurality of fingers 262 configured to cooperatively receive theextension portion 252 of endplate 250. A plurality of relief spaces orslots 264 are radially spaced between fingers 262 to allow fingers 262to bend or flex radially.

In a preferred embodiment, the locking ring 256 has a generally annular,c-shape and includes an exterior wall 266, an interior wall 268, andends 277, 279. The interior wall 268 preferably defines and interiorportion 255. In a preferred embodiment, the interior wall 268 includes aplurality of channel 270 which are spaced radially along the lockingring 256. The channels 270 allow the locking ring 256 to bend or flexradially. The ends 277, 279 each include openings 280, 282 which may bepartially threaded. A locking element 284 is configured and dimensionedto be threadingly received in the openings 280, 282. It alsocontemplated that that locking element 284 can engage the ends 277, 279by other non-threaded means, such as a sliding fit.

With continued reference to FIGS. 11-13, in a preferred embodiment, theendplate 250 includes a plurality of mounting holes 286 spaced aroundthe perimeter of the endplate 250 for receiving insertable bone engagingmembers. In one embodiment, bone engaging members, comprise conicalspikes each having a cylindrical base portion configured to fit withinholes 286, for instance, by press-fit or by threaded engagement. Inalternate embodiments, differently shaped bone engaging members may beused, or in other embodiments no bone engaging members may be used.According to one preferred embodiment, endplate 250 has chamfered edges288 around the perimeter to facilitate insertion and/or accommodate theshape of the vertebral bodies which they engage. The superior or boneengaging surfaces 290 of endplate 250 may also include numerous types oftexturing to provide better initial stability and/or grasping contactbetween the end plate and the respective vertebrae. In a preferredembodiment, the texturing is a plurality of teeth 292. In preferredembodiments where the implant is manufactured from PEEK or other plasticmaterials, the endplate 250 may also include radio-opaque material, suchas tantalum markers 294, which aid in providing location markers inradiographic images.

In an exemplary use, during the implant installation and expansion tothe desired position, the endplate 250 can move in poly-axial fashionwith respect to the implant to accommodate the anatomy of the adjacentvertebral body as well as accommodate the natural curvature of thespine, such as kyphosis and lordosis. More specifically, the arcuateextension portion 252 is free to move in the interior portion 253 of thereceiving portion 254. The fingers 262 are generally compliant and canflex to accommodate the movement of the arcuate extension portion 252.Once the desired positioning of the endplate 250 is achieved, theendplate 250 can be locked in place. The endplate 250 is locked in placeby actuating the locking element 284. As the element 284 engages thethreading in opening 280,282 the ends 277, 279 of the locking ring 256are brought closer together contracting the ring 254 and reducing thesize of the interior portion 255. As the ring 254 contracts, the fingers262 of the receiving member 254, abutting against the inner wall 268,are flexed radially inwardly pushing against the extension portion 252.As a result, the endplate 250 is locked in place.

Referring now to FIGS. 14-19, an angling inserter tool 300 is shown thatmay be used to expand the implant 10 in accordance with embodiments ofthe present invention. The tool 300 is configured to hold the implant10. As illustrated, the angling inserter tool 300 may comprise a handleportion 302, a cylindrical base portion 304, and a tip assembly 306. Inpreferred embodiments, the cylindrical base portion 304 is disposedbetween the handle portion 302 and the tip assembly 306. As best seen inFIG. 14, the angling inserter tool 300 has a longitudinal or tool axis308 that passes through the tool 300 from proximal end 310 to distal end312. The tip assembly 306 can be angled relative to the tool axis 308,for example, allowing the implant to be placed around or behind certainanatomical structures. As best seen in FIGS. 18 and 19, the tool 300includes a primary gear mechanism (e.g., gears 356, 410, 412, 414, 416),for example, configured to drive gear member 16 on the implant 10 itholds, and the tool 300 also includes a second gear mechanism (e.g.,distal gear 368, central gear 402, proximal gear portion 398), forexample, configured to attached or release the implant 10 from the tool300.

In some embodiments, the cylindrical base portion 304 includes an outercylinder 314. At distal end 312, the outer cylinder 314 preferablyincludes arms 316 that extend distally from the outer cylinder 314, asbest seen in FIGS. 18 and 19. One of the arms 316 may include a bentportion 317 at least a portion of which extends radially outward fromthe outer cylinder 314. Each of the arms may include an opening 318. Theopenings 318 in each of the arms 316 may be axially aligned andconfigured to receive a pin 376, as best seen in FIGS. 18 and 19. Thepin 376 may rotatably secure the tip assembly 306 to the cylindricalbase portion 304 allowing the tip assembly 306 to angulate with respectto the tool axis 308.

Referring to FIGS. 15-19, in some embodiments, the cylindrical baseportion 304 also includes an internal shaft 320. As illustrated, theinternal shaft 320 may be coaxial with the outer cylinder 314 whereinthe internal shaft 320 is received within the outer cylinder 314. Inpreferred embodiments, the internal shaft 320 is a generally cylindricalbody. In present embodiments, the internal shaft 320 can translatelongitudinally with respect to the outer cylinder 314. In a preferredembodiment, the internal shaft 320 has an angulated distal end 322,which may be offset from tool axis 308. As best seen in FIG. 19, theangulated distal end 322 may include tabs 324 which may each include anopening 326. The openings 326 in each of the tabs 324 may be axiallyaligned and configured to receive a pin 328 as shown on FIG. 19. The pin328 may secure the internal shaft 320 to a linking arm 330 coupling thetip assembly 306 to the internal shaft 320.

With reference now to FIGS. 14-17, embodiments of the cylindrical baseportion 304 also include a knob 332 generally configured to effecttranslation of the internal shaft 320 with respect to the outer cylinder314. In the illustrated embodiment, the knob 332 is disposed on theouter cylinder 314. At least a part of the knob 332 may include internalthreads 334, as best seen in FIG. 15. In a preferred embodiment, theinternal threads 334 engage one or more blocks 336, as best seen inFIGS. 15 and 17. With continued reference to FIGS. 15 and 17, the blocks336 are received in one or more openings 338 in the internal shaft 320and extend through one or more windows 340 in the outer cylinder 314 toengage the internal threads 334 of the knob 332. As illustrated, thewindows 340 in the outer cylinder 314 may be longer than the blocks 336,allowing the blocks 336 to move longitudinally in the windows 340.Accordingly, rotation of the knob 332 on the outer cylinder 314 shouldcause the blocks 336 to move thereby causing the internal shaft 320 totranslate within the outer cylinder 314. The internal shaft 320 mayextend through the outer cylinder 314 or retract into the outer cylinder314, depending for example on the direction of the rotation of the knob332. Because the linking arm 330 couples the internal shaft 320 to thetip assembly 306, translation of the internal shaft 320 should move thetip assembly 306 causing rotation of the tip assembly about the pin 376,as best seen in FIGS. 22 and 23. Accordingly, rotation of the knob 332on the outer cylinder 314 should cause the blocks 336 to move therebycausing the internal shaft 320 to translate within the outer cylinder314. The internal shaft 320 may extend through the outer cylinder 314 orretract into the outer cylinder 314, depending for example on thedirection of the rotation of the knob 332. Referring now to FIGS. 22 and23, because the linking arm 330 couples the internal shaft 320 to thetip assembly 306, translation of the internal shaft 320 should move thetip assembly 306 causing rotation of the tip assembly 306 about the pin376. For example, advancement of the internal shaft 320 through theouter cylinder 314 should effect rotation of the tip assembly 306 aboutthe pin 376 in a first direction (as best seen in FIG. 22), whileretraction of the internal shaft into the outer cylinder 314 shouldeffect rotation of the tip assembly 306 about the pin 376 in an oppositedirection (as best seen in FIG. 23). Rotation of the tip assembly 306may be monitored using viewing window 342 and visual indicators 344. Asillustrated by FIGS. 22 and 23, visual indicators 344 may be disposed onthe internal shaft 320. The visual indicators 344 may be markings, suchas numbers, etchings, lines, combinations thereof, or the like, thatprovide a visual indication of the degree of rotation. The visualindicators 344 on the internal shaft 320 may generally aligned with aviewing window 342 in the outer cylinder 314. The visual indicators 344should allow accurate measurement of the angulation of the tip assembly306 even when the tip assembly 306 itself may be obscured from viewing.

With continued to reference to FIGS. 14-17, ring 346 may secure the knob332 on the outer cylinder 314 in accordance with embodiments of thepresent invention. As illustrated, the ring 346 may be disposed on theouter cylinder 314 proximally to the knob 332. A set screw 348 disposedthrough opening 350 in the ring 346 may engage opening 352 in the outercylinder 314 to secure the ring 346 on the outer cylinder 314.

Referring to FIGS. 15 and 17-19, embodiments of the cylindrical baseportion 304 also include a primary drive shaft 354. As illustrated, theprimary drive shaft 354 may be coaxial with the internal shaft 320wherein the primary drive shaft 354 is receiving within the internalshaft 320. In preferred embodiments, the primary drive shaft 354 may bea generally cylindrical body. As best seen on FIGS. 18 and 19, theprimary drive shaft 354 includes a distal gear 356, which may be a bevelgear, for example. In certain embodiments, the distal gear 356 isconfigured to fixedly engage distal end 358 of the primary drive shaft354, as best seen in FIG. 19. In present embodiments, the primary driveshaft 354 may be configured to rotate with respect to the internal shaft320. A driving instrument (not shown) may be used to rotate the primarydrive shaft 354. The driving instrument may engage the primary driveshaft 354 at proximal end 310 through opening 360 of handle portion 302,as best seen in FIG. 15. As will be discussed in more detail below, thedistal gear 356 may be configured to engage one or more correspondinggears (e.g., gears 412, 414, 416) in the tip assembly 306 to causerotation of implant engagement gear 410 (see, e.g., FIGS. 18 and 19).

In some embodiments, the cylindrical base portion 304 also includes asecondary drive shaft 366. As illustrated, the secondary drive shaft 366may be coaxial with the primary drive shaft 354 wherein the secondarydrive shaft 366 is received the primary drive shaft 354. As best seen inFIGS. 18 and 19, the secondary drive shaft 366 includes a gear 368 atdistal end 312, which may be a bevel gear, for example. In presentembodiments, the secondary drive shaft 366 may be configured to rotatewith respect to the primary drive shaft 354. A driving instrument (notshown) may be used to rotate the secondary drive shaft 366. The drivinginstrument may engage the secondary drive shaft 366 at the proximal end310 through the opening 360 in the handle portion, as best seen in FIG.15. As will be discussed in more detail below, the gear 368 may beconfigured to engage one or more corresponding gears (e.g., gear 402,gear portion 398) in the tip assembly 306 to cause extension of centralshaft 392 (see, e.g., FIGS. 18 and 19).

Referring to FIGS. 14-17, the handle portion 302 includes a cylindricalportion 362 and a handle 364. As illustrated, the handle 364 maypreferably extend downward from the cylindrical portion 362. Opening 360may be disposed in the handle portion 302 at the proximal end 310 sothat the secondary drive shaft 366 and the primary drive shaft 354 canbe accessed. At least a portion of the cylindrical base portion 304 maybe disposed in the cylindrical portion 362. As best seen in FIG. 17, alocking member 365 may engage the outer cylinder 314 of the cylindricalbase portion 304 to secure the cylindrical base portion 304 to thehandle portion 302. The locking member 365 may extend through an openingin the cylindrical portion 362.

Referring to FIGS. 18-21, the tip assembly 306 will now be described inmore detail in accordance with embodiments of the present invention. Inpreferred embodiments, the tip assembly 306 includes an upper plate 372and a base portion 374. The upper plate 372 and the base portion 374 maybe secured to one another by one or more pins 388. In the illustratedembodiment, two pins 388 are used to secure the upper plate 372 and thebase portion 374. As illustrated, the pins 388 may be configured to bereceived in openings 386 in the upper plate 372 and openings 390 in thebase portion 374.

As previously described, the tip assembly 306 may be rotatably securedto the cylindrical base portion 304 with the pin 376. In the illustratedembodiment, the pin 376 is received in an opening 378 in upper tab 380of the upper plate 372 and in opening 382 in lower tab 384 of the baseportion 374. A bushing 385 may be disposed about at least a portion ofthe pin 376. The pin 376 has a pin axis 377 (as shown on FIG. 18) aboutwhich the tip assembly 306 may rotate. Referring to FIGS. 19-21, theupper plate 372 may further include an outer tab 406 having acorresponding opening 408. The outer tab 406 may be offset from the toolaxis 308 and configured to receive the pin 404. The pin 404 may securethe tip assembly 406 to the linking arm 330 coupling the tip assembly306 to the internal shaft 320. Accordingly, advancement or retraction ofthe internal shaft 320 should cause rotation of the tip assembly 306about the pin axis 377.

As illustrated by FIGS. 18-21, the tip assembly 306 preferably furtherincludes a central shaft 392 disposed in through-bore 394 (as best seenon FIG. 19) in the base portion 374. The central shaft 392 preferablymay include a threaded distal tip portion 396 that extends distallybeyond the implant engagement gear 410 to facilitate location andmounting of the angling inserter tool 300 with the implant 10 (see,e.g., FIG. 2) in accordance with embodiments of the present invention.The central shaft 392 may also include a proximal gear portion 398 thatengages corresponding gears to facilitate extension of the central shaft392 through the through-bore 394. For example, as best seen on FIGS. 18and 19, the proximal gear portion 398 may engage a secondary centralgear 402, which may be a bevel gear. The secondary central gear 402 maybe disposed about the pin 376 and rotate about the pin axis 377. Thesecondary central gear 402 may engage gear 368 on the secondary driveshaft 366 of the cylindrical base portion 304. Accordingly, rotation ofthe secondary drive shaft 366 about the tool axis 308 should causerotation of the secondary central gear 402 about the pin axis 377 whichshould in turn drive the proximal gear portion 398 causing rotation ofthe central shaft 392 and movement of the central shaft through thethrough-bore 394. The central shaft 392 should extend through the baseportion 374 or retract into the base portion 374, depending for exampleon the direction of rotation of the secondary drive shaft 366.

With continued reference to FIGS. 18-21, the tip assembly 306 preferablyfurther includes an implant engagement gear 410. In preferredembodiments, the implant engagement gear 410 is configured to engageteeth 74 of the gear member 16 of the implant 10 (see, e.g., FIG. 2)such that when the implant engagement gear 410 is rotated, the gearmember 16 of the implant 10 is rotated about the longitudinal axis 18and the inner member 12 translates along the longitudinal axis to eitherexpand or contract the implant 10. A series of gears (e.g., gears 412,414, and 416) transfer rotation of the primary drive shaft 354 to theimplant engagement gear 410. For example, rotation of implant engagementgear 410 causes rotation of distal gear 356. The distal gear 356 mayengage a first primary central gear 412 disposed on the pin 376 suchthat rotation of the distal gear 356 causes rotation of the firstprimary central gear 412 about the pin axis 377. The first primarycentral gear 412 may be a bevel gear, for example. The distal gear 356and the first primary central gear 412 may have rotational axes that areperpendicular, for example, the tool axis 308 and the pin axis 377. Asecond primary central gear 414 may be fixedly engaged to the firstprimary central gear 412 such that rotation of the central gear 412causes rotation of the second primary central gear 414. The secondprimary central gear 414 may engage secondary transfer gear 416 suchthat rotation of the second primary central gear 414 causes rotation ofthe primary transfer gear 416. The gears 414, 416 may each be spurgears, for example. Pin 418 may secure primary transfer gear 416 toupper plate 372. The primary transfer gear 416 may rotate about the pin418. The primary transfer gear 416 may engage the implant engagementgear 410 such that rotation of the primary transfer gear 416 causesrotation of the implant engagement gear 410. Accordingly, when theprimary drive shaft 354 is rotated, the implant engagement gear 410rotates causing the implant 10 to either expand or contract.

In an exemplary use of the angling inserter tool 300 with the implant10, the angling inserter tool 300 initially engages the slots 52 of theimplant 10 via the arms 400 and implant engagement gear 410 engages gearmember 16 via their respective teeth. The secondary drive shaft 366 maythen be driven (e.g., rotated) causing the second gear mechanism (e.g.,distal gear 368, central gear 402, proximal gear portion 398) to advancethe central shaft 392. For example, rotation of the secondary driveshaft 366 rotates the distal gear 368 about the tool axis 308 whichrotates the secondary central gear 402 about the pin axis 376 whichrotates the proximal gear portion 398 about the tool axis 308 to causethe central shaft 392 to advance toward opening 54. The threaded tipportion 396 enters into the opening 54 engaging the threads in opening54 as well as engaging the through-hole 84 of locking member 80. Asdiscussed previously, the locking member 80 should be engaged such thatthe gear member 16 may rotate freely. The implant 10 may then be placedin a desired location, for example, in the vertebral space. If desired,the tip assembly 306 can be angled relative to the tool axis 308,allowing the implant to be placed around or behind certain anatomicalstructures. As previously described, the knob 332 on the tool 300 may berotated to cause the tip assembly 306 to angulate. For example, rotationof the knob 332 may cause longitudinal movement of the blocks 336 tocause translation of the internal shaft 320, thus moving the tipassembly 306 and causing rotation of the tip assembly 306 about the pin376. The primary drive shaft 354 may then be driven (e.g., rotated)causing the primary gear mechanism (e.g., gears 356, 410, 412, 414,416), for example, to rotate the gear member 16 on the implant 10. Forexample, rotation of the primary drive shaft 354 rotates the distal gear356 about the tool axis 308 which rotates the first primary central gear412 about the pin axis 377 which rotates the second primary central gear414 about the pin axis 377. Rotation of the second primary central gear414 rotates the primary transfer gear 416 about an axis generallyparallel to the pin axis 377 which rotates the implant engagement gear410 about an axis generally parallel to pin axis 377. The implantengagement gear 410 engages the gear member 16 on the implant causingthe gear member 16 to rotate about longitudinal axis 18. As discussedabove, the rotation of the gear member 16 results in the movement of theinner member 12 causing the implant 10 to either expand or contract,depending on the direction the gear member 16 is rotated. Once thedesired height for the implant 10 is reached, the angling inserter tool300 may be disengaged from the implant 10. It should be understood thatthe angling inserter tool 300 can be disengaged from the implant 10 evenwith the tip assembly 306 at any angle with respect to the tool axis308. When the tool 300 is removed, the locking member 80 returns back toits initial state, thus preventing the gear member 16 from rotating aspreviously described.

While the preceding description of the angling inserter tool 300 is withrespect to the implant 10, it should be understood that embodiments ofthe angling inserter tool 300 may be used for insertion and expansion ofany of a variety of expandable implants for implantation into the spine,including vertebral body spacers for vertebral body replacement andexpandable cages for insertion into the disc space.

Referring to FIGS. 24-27, an expandable trial assembly 420 is shown thatmay be used in the implanting of an expandable implant, such as implant10 (FIG. 2), in accordance with embodiments of the present invention. Inpreferred embodiments, the trial assembly 420 may be used to distractadjacent vertebral bodies and to give a measurement of the distraction.In this manner, the trial assembly 420 may give a measurement of thedesired height for the subsequent expansion of the implant 10, forexample. As illustrated, the expandable trial assembly 420 may comprisea handle portion 422, a cylindrical base portion 424, and an expandabletip assembly 426. In the illustrated embodiment, the handle portion 422extends downward from the cylindrical base portion 424. As illustrated,the expandable tip assembly 426 may be disposed at the distal end 432 ofthe cylindrical base portion 424. The expandable trial assembly 420 hasa tool axis 428 that extends through the trial assembly 420 from theproximal end 430 to the distal end 432 of the cylindrical base portion424.

In preferred embodiments, the cylindrical base portion 424 may includean outer cylinder 434 and a drive shaft 436. The drive shaft 436 may becoaxial with the outer cylinder 434 wherein the drive shaft 436 isinside the outer cylinder 434. In preferred embodiments, the drive shaft436 is a generally cylindrical body. In present embodiments, the driveshaft 436 can rotate about the tool axis 428. A distal gear 438 islocated on the drive shaft 436 at the distal end 432, as best seen inFIGS. 25 and 27. Rotation of the drive shaft 436 rotates the distal gear438. The teeth of the distal gear 438 are not illustrated forsimplicity.

Referring to FIGS. 24, 26, and 28-29, the cylindrical base portion 424further includes scale 440 at proximal end 430. The scale 440 may be inthe general form of a cylindrical section. As best seen in FIGS. 28 and29, at least a portion of the scale 440 may be internally threaded withthreads. The scale 440 may be keyed to the outer cylinder 434. Forexample, locking mechanism 444 may secure the scale 440 to the outercylinder 434, as best seen in FIG. 28. As seen in FIGS. 26 and 29, atleast a portion of the drive shaft 436 may be threaded, for example, inthe general region of the scale 440. The threaded portion 446 of thedrive shaft 436 may engage the threads of the scale 440. Accordingly,rotation of the drive shaft 426 should cause the scale 440 to movelongitudinally. Visual indicators 448, 450 may be placed on the scaleand/or the outer cylinder 434 to show, for example, the amount ofexpansion of the expandable tip assembly 426. The visual indicators 448,450 may be in the form of numbers, lines, combinations thereof or thelike etched or otherwise formed on the scale 440 and/or the outercylinder 434. In preferred embodiments, the scale 440 also includes aviewing window 452.

Referring to FIGS. 24-27, the expandable tip assembly 426 will now bedescribed in more detail in accordance with embodiments of the presentinvention. As illustrated, the expandable tip assembly 426 may include ahousing 454 which may be in the form of a rounded end. The expandabletip assembly 426 further may include an outer member 456 and an innermember 458 which may be telescopingly received within the inner member458 and the outer member 456. The outer member 456 may generallycomprise a generally cylindrical body 460 having external threads 462 onat least a portion thereof. An endplate 464 may be coupled to the outermember 456. The inner member 458 may comprise a generally cylindricalbody 466 having external threads 468 on at least a portion thereof. Anendplate 470 may be coupled to the inner member 458. While trialendplates 464, 470 are shown on the tip assembly 426, it should beappreciated that endplates having a different footprint may be used inaccordance with embodiments of the present invention. For example, theendplates 464, 470 may be articulating (e.g., ball and socket typejoint) to allow for measurement of sagittal alignment/angulation inaddition to height. A One or more pins 472 may be used to secure theinner and outer members 456, 458 from rotational movement. The pins 472may be disposed in corresponding slots 474 (best seen in FIG. 26) of theinner and outer members 456, 458.

In preferred embodiments, the expandable tip assembly 426 may furtherinclude upper gear member 476 and lower gear member 478. While notillustrated, the upper and lower gear members 476, 478 may each includeouter gear teeth on at least a portion of their exterior surfaces thatengage the distal gear 438 of the cylindrical base portion 424.Accordingly, rotation of the distal gear 438 about the tool axis shouldcause the upper and lower gear members 476, 478 to each rotate about thetip axis 480, as best seen in FIGS. 25 and 27. The upper gear member 476is engaged with the external threads 462 of the outer gear member 458and the lower gear member 478 is engaged with the external threads 468of the inner member 458. Accordingly, because the outer and innermembers 456, 458 are locked in rotational position by the one or morepins 472, rotation of the upper and lower gear members 476, 478 shouldcause the tip assembly 426 to either expand or contract. For example,rotation in one direction should cause the endplates 464, 470 to expand(or translate vertically outward) while rotation in the oppositedirection should cause the endplates 464, 470 to contract (or translatevertically inward).

In an exemplary use of the expandable trial assembly 420, the trialassembly 420 may be inserted into a desired position in a patient'sspine, for example, in a vertebral space, in a contracted position, asshown in FIGS. 24 and 25. The drive shaft 436 may then be rotated whichcauses expansion of the expandable tip assembly 426. FIGS. 26 and 27illustrate the tip assembly 426 in an expanded position. For example,rotation of the drive shaft 436 rotates the distal gear 438 about thetool axis 430 which in turn rotates upper gear member 476 and lower gearmember 478 about the tip axis 480. Rotation of the upper gear member 476and the lower gear member 478 results in movement of the outer member456 and the inner member 458 causing the expandable tip assembly 426 toeither expand or contract, depending on the direction the drive shaft436 is rotated. Once the desired expansion for the tip assembly 426 isreached, the expansion can be measured using the scale 440 at proximalend 430. The tip assembly 426 can then be contracted by rotation of thedrive shaft 436 and then removed from the patient's body. An expandableimplant, such as implant 10, can then be positioned in the patient'sbody in a manner that will be evident to one of ordinary skill in theart with the benefit of this disclosure. Once positioned in the body,the expandable implant can then be expanded to a desired expansion basedon the measured expansion of the expandable trial assembly 420.

While the invention herein disclosed has been described by means ofspecific embodiments and applications thereof, numerous modificationsand variations can be made thereto by those skilled in the art withoutdeparting from the scope of the invention as set forth in the claims.

1. A method of inserting an implant, comprising: providing a trialassembly; positioning the trial assembly between vertebrae in a patient;rotating a drive shaft of the trial assembly to cause upper and lowergear members of the trial assembly to rotate causing expansion of a tipassembly of the trial assembly; measuring expansion of the trialassembly with a scale at a proximal end of the trial assembly; removingthe trial assembly from the patient; positioning an implant between thevertebrae in the patient; and expanding the implant based on themeasured expansion of the trial assembly.
 2. The method of claim 1,wherein the step of rotating the drive shaft causes rotation of a gearat distal end of the drive shaft about a longitudinal axis of the trialassembly, wherein rotation of the gear causes rotation of the upper andlower gear members.
 3. The method of claim 2, wherein rotation of theupper gear member causes movement of an outer member, wherein rotationof the lower gear member causes movement of an inner member.
 4. Themethod of claim 3, wherein the inner member is telescopingly received inthe outer member, and wherein the inner member advances from the outermember.
 5. The method of claim 1, wherein measuring expansion of thetrial assembly comprises viewing markings on the drive shaft through aviewing window in a scale.
 6. The method of claim 5, wherein the driveshaft threadingly engages the scale.
 7. The method of claim 5, whereinthe step of rotating the drive shaft causes movement of the scale withrespect to the drive shaft.
 8. The method of claim 1, wherein the stepof removing the trial assembly from the patient comprises rotating thedrive shaft of the trial assembly in an opposite direction to cause theupper and lower gear members of the trial assembly to rotate causingcontraction of the tip assembly of the trial assembly.
 9. The method ofclaim 1, wherein expanding the implant comprises rotating a gear memberon the implant to cause expansion of the implant.
 10. The method ofclaim 9, wherein rotation of the gear member results in movement of aninner member causing the implant to expand.
 11. The method of claim 9,wherein expansion of the trial assembly distracts the vertebrae betweenwhich the trial assembly is positioned.
 12. A system for inserting animplant comprising: a trial assembly configured for insertion betweenvertebrae in a patient, wherein the trial assembly comprises: a handleportion; a cylindrical base portion coupled to the handle portion,wherein the cylindrical base portion comprises: an outer cylinder; adrive shaft configured to be coaxially received in the outer cylinder,wherein the drive shaft includes a gear at its distal end, wherein thedrive shaft is configured to rotate about a longitudinal axis of thecylindrical base portion; and a scale configured to threadingly receivethe drive shaft within the scale; and a tip assembly configured toexpand, wherein the tip assembly comprises: an outer member; an uppergear member configured to engage the gear on the drive shaft and engagethe outer member; an inner member configured to be coaxially receivedwithin the outer member; and an upper gear member configured to engagethe gear on the drive shaft and engage the outer member, wherein thescale is configured to measure expansion of the tip assembly. anexpandable implant configured for insertion into a patient's spine, theexpandable implant having a longitudinal axis and comprising a gearmember configured to expand the expandable implant; and an expandableimplant configured to be inserted between the vertebrae in the patient.13. The system of claim 12, wherein the scale is keyed to the outercylinder.
 14. The system of claim 12, wherein the outer cylindercomprises one or more visual indicators of the expansion of the trialassembly, and wherein the scale includes a viewing window for the one ormore visual indicators.
 15. The system of claim 14, wherein the scalecomprises one or more visual indicators of the expansion of the trialassembly.
 16. The system of claim 12, wherein an endplate for engaging afirst vertebral body is coupled to the inner member, and wherein anendplate for engaging a second vertebral body is coupled to the outermember.
 17. The system of claim 12, wherein a pin secures the inner andouter members in rotational position with respect to one another. 18.The system of claim 12, wherein the expandable implant comprises: aninner member having a hollow interior portion and a threaded externalportion and including a first end portion configured to engage the firstvertebral body; and an outer member having a hollow interior portionconfigured to coaxially receive the inner member therein and including asecond end portion configured to engage a second vertebral body, whereinthe inner and outer members are moveable relative to each other alongthe longitudinal axis of the expandable implant; a gear memberpositioned coaxial to the inner member and the outer member and axiallyfixed to the outer member and freely rotatable with respect to the outermember, wherein the gear member threadingly engages the threaded portionof the inner member.
 19. The system of claim 12 further comprising atool having a longitudinal axis and configured for insertion of theexpandable implant between the vertebrae, wherein the tool comprises: ahandle portion; a cylindrical base portion coupled to the handleportion, wherein the base portion comprises: an outer cylinder; aninternal shaft configured to be coaxially received within the outercylinder; a primary drive shaft configured to be coaxially receivedwithin the internal shaft; and a secondary drive shaft configured to becoaxially received within the primary drive shaft; and a tip assembly ata distal end of the base portion, wherein the tip assembly comprises abase portion and a central shaft disposed in a through-bore in the baseportion, wherein the central shaft is configured to engage theexpandable implant; a primary gear mechanism configured to transferrotation of the primary drive shaft to the expandable implant to causeexpansion of the expandable implant; and a secondary gear mechanismconfigured to transfer rotation of the secondary drive shaft to thecentral shaft, wherein the internal shaft is configured to engage thetip assembly such that the tip assembly is configured to rotate about apin coupled between the base portion and the tip assembly upon distaladvancement of the internal shaft.
 20. A trial assembly configured forinsertion between vertebrae in a patient, comprising: a handle portion;a cylindrical base portion coupled to the handle portion, wherein thecylindrical base portion comprises: an outer cylinder; a drive shaftconfigured to be coaxially received in the outer cylinder, wherein thedrive shaft includes a gear at its distal end, wherein the drive shaftis configured to rotate about a longitudinal axis of the cylindricalbase portion; and a scale configured to threadingly receive the driveshaft within the scale; and a tip assembly configured to expand, whereinthe tip assembly comprises: an outer member; an upper gear memberconfigured to engage the gear on the drive shaft and engage the outermember; an inner member configured to be coaxially received within theouter member; and an upper gear member configured to engage the gear onthe drive shaft and engage the outer member, wherein the scale isconfigured to measure expansion of the tip assembly.